1. Field of the Invention
This invention relates to the testing of integrated circuit chips on semi-conductor wafers and, more particularly, to apparatus for supporting a probe card during the testing of the integrated circuits.
2. Description of the Prior Art
Integrated circuits are formed as discrete chips on round semi-conductor wafers. The integrated circuit chips are tested prior to the cutting of the wafer. Typically, chips are tested by computer operated test apparatus that exercises the circuits on the chips.
A probe card is an element which includes a plurality of electrical leads, and the leads make contact with the various circuit elements on the integrated circuit chip being tested. In the prior art, it is typical for probe cards to be built by attaching metal needles to an epoxy ring. The needles or probe elements may be secured to the ring by epoxy or they may be bonded, as by welding, to a blade. The needles are individually placed on the desired electrical elements of the chips for testing.
U.S. Pat. No. 3,849,728 (Evans) discloses a probe card for testing integrated circuit patterns. The apparatus includes a plurality of needles secured to needle holders, and the needle holders are in turn secured to conductive elements on a printed circuit board. The elements are all fixed relative to each other.
U.S. Pat. No. 3,939,414 (Roch) discloses an integrated circuit testing apparatus in which a test probe assembly includes elements for the precise location of a test probe both axially and vertically.
U.S. Pat. No. 4,161,692 (Tarzwell) discloses another type of probe device with probe needles secured to holder elements. The patent is primarily directed to the holder elements for the probe needles.
U.S. Pat. No. 4,518,914 (Okubo et al) discloses test probe apparatus which includes a probe card and needles extending outwardly and downwardly from the probe card. The probe card is secured to a base plate by vacuum pressure.
U.S. Pat. No. 4,636,722 (Ardezzone) discloses test probe apparatus which includes a cutout portion and an element disposed in the cutout portion adjacent to a probe assembly. The cutout portion of the Ardezzone patent actually includes two "inserts" one of which is disposed on the top of the apparatus and extends into the cutout portion, and the second is the one referred to above, that is secured to the bottom of the cutout portion and makes contact with the probe assembly.
U.S. Pat. No. 4,757,256 (Whann et al) discloses an epoxy ring probe card apparatus in which a plurality of probe elements are secured to conductive traces on the epoxy ring.
U.S. Pat. No. 4,758,785 (Rath) discloses integrated circuit testing apparatus in which a probe card includes a plurality of probe elements and a pressure pad disposed against the probe and secured to support structure by resilient attaching elements to provide vertical movement of the pressure pad relative to the probe for providing a desired pressure of the probe against an integrated circuit to be tested.
U.S. Pat. No. 4,764,723 (Strid) discloses another type of probe apparatus. The '723 apparatus is primarily directed to electrical connections involved.
U.S. Pat. No. 4,791,363 (Logan) discloses another type of probe needle apparatus. The probe needle apparatus includes a ceramic body, with a microstrip circuit element on one side of the ceramic body and a ground plane on the other side of the ceramic body. The probe apparatus of the '363 patent is designed primarily for frequencies in the Gigahertz range.
U.S. Pat. No. 4,891,585 (Janko et al) discloses another type of probe apparatus in which pressure contacts are made between the probe card apparatus and circuit elements on a wafer being tested.
U.S. Pat. No. 4,899,099 (Mendenhall et al) which includes what is referred to as a flex dot wafer probe. The '099 apparatus appears to use thin film technology.
U.S. Pat. No. 4,906,920 (Huff et al) discloses a self-leveling membrane probe apparatus. The apparatus includes another carrier element and translation means disposed in a relatively movable relationship to the carrier. Spring elements secure the carrier in the translation elements together.
U.S. Pat. No. 4,912,399 (Greub et al) discloses another type of probe apparatus. The probe apparatus uses contact elements on the bottom of a support member, and the support member is used to provide a pressure contact between the contact elements and the circuit elements under test.
U.S. Pat. No. 4,918,383 (Huff et al) discloses probe card apparatus with an automatic contact scrub action. The automatic scrub action is accomplished by using fixed length and variable length flexure assemblies. The combination of fixed and variable length pivot assemblies results in a lateral or sideways movement of probe contact elements which provides an automatic scrubbing action of the contact element against the device under test.
The apparatus of the present invention utilizes individual needles on a probe card, and the needles are bent downwardly at an angular orientation from the horizontal to provide a scrubbing action on the integrated circuit elements as the needles make contact with the integrated circuit. The scrubbing action provides a cleaning for insuring that good electrical contact is made between the needles of the probe card and the circuit elements. The needles comprise continuation of conductive traces on a probe card dielectric substrate.
The probe card of the present apparatus is secured to a probe card holder that includes a movable or adjustable element which makes contact with the probe card. A dielectric block insert in the probe card bolder is adjustable to provide a desired force on the probe card needles.